The disclosure describes methods and inhalers that deagglomerate dry powder using inspiratory effort of a user of an inhaler. Inhaler fin and mesh configurations are described that facilitate deagglomeration. At least in steady state conditions, a dry powder and airflow pattern can be generated having turbulence with flow vortices, some of which may have a vortex having an axis of rotation that extends in an inspiratory flow direction while others may have a vortex that is substantially orthogonal to the inspiratory flow direction in an inspiratory airflow path, as an amount of dry powder travels through the inhaler to thereby deagglomerate the dry powder without trapping undue amounts of the dry powder during inhalation.